PITTSBURGH — A judge has rejected a request for a mistrial by the defense attorneys for suspended state Supreme Court Justice Joan Orie Melvin. Melvin’s attorneys asked for the mistrial today because the justice’s former law clerk testified Friday that a handwritten document from the judge was a request to fill out a campaign endorsement questionnaire in 2003. In reality, the document was from 1998 and had nothing to do with political campaigning, which Melvin is accused of doing illegally using her former Superior Court staff. The judge rejected the mistrial request after prosecutors acknowledged making an honest mistake with the document and the jury was instructed today to disregard that evidence.